Frontiers in Understanding Climate Change and Polar Ecosystems Report of a Workshop (2011) / Chapter Skim
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1 Introduction
1 Introduction
Pages 5-24
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. A key mechanism driving increased warming in the polar regions is the albedo feedback effect caused by variations in sea-ice cover, snow cover, and in the Arctic (broadly defined herein to include northern treeline boreal vegetation)
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6 FRONTIERS IN UNDERSTANDING CLIMATE CHANGE AND POLAR ECOSYSTEMS FIguRE 1.1 Map of the Arctic and Antarctic regions. SOURCE: Figure 15.1 in IPCC (2007c)
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areas of research and technology advances needed to better understand the changes occurring in polar ecosystems. Participants were invited from a broad range of disciplines across the Arctic and the Antarctic including (but not limited to)
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Once under way, the change will proceed at the speed given by the internal ecosystem dynamics, even if the forcing is removed (implies a loss of control)
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. The effects are manifested as atmospheric warming, decreasing extent and duration of sea ice cover, glacier retreat, permafrost thawing, increasing river discharge, loss of snow cover, and shifting ecosystem structure and function.
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The connectivity between fine and broad-scale properties is increasingly recognized as key to understanding ecosystem dynamics, particularly as global temperatures increase over time. Recent environmental changes are having broad-scale ecosystem impacts at lower trophic levels that have the capability to cascade to higher trophic organisms and the effects of changes in the cryosphere will likely cascade throughout the entire ecosystem (Wassmann, 2008)
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ocean e.g. changes in acidification biodiversity e Bi her Ecosystem Connectivity, p osp h Vulnerability, and os er e tm Resilience including A Human Dimensions Geos phere FIguRE 1.2 Schematic illustrating the connectivity among the earth system components and climate change in the context of the three workshop themes, including examples of changes that could drive an ecosystem response.
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, which has further impacts on air temperature, ocean temperature and currents, sea ice and glaciers, and winds. These impacts will affect humans and ecosystems and, in turn, the human and ecosystem responses will feed back into the components of the system.
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Models may focus on any particular subcomponent, for example, a polar coastal system including subsistence-based human communities, the Northern or Southern Annular Modes, and the Greenland or West Antarctic Ice Sheets. At higher levels of organization, a reduced-complexity model might include simplified parameterizations of each of these subcomponents in a model of the "full" Polar System.
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and the Antarctic (climate change in the McMurdo Dry Valleys ecosystem) terrestrial ecosystems.
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. Recent investigations have revealed that most populations of Alaska's interior boreal forests, including the dominant tree species white spruce (Picea glauca)
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Arctic Example: Subsistence Impacts In Arctic subsistence communities, a host of changes related to climate have been noted over the last decade. For example, higher than usual air temperatures and extreme weather events are becoming more common.
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Thawing permafrost can cause damage to infrastructure including ice cellars, which are used in long term storage of traditional foods. Melting can occur during the winter months as well as summer.
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Antarctic Example: Climate Change in the McMurdo Dry Valleys Ecosystem On the Antarctic continent, warming is also occurring faster than expected in certain areas; the Antarctic Peninsula has warmed five times faster than the global average, and the warming of the southern ocean and associated loss of sea ice has resulted in a shift in penguin species and their food sources (McClintock et al., 2008; Montes-Hugo et al., 2009)
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Summer cooling is particularly important to the McMurdo Dry Valley ecosystem because temperatures are poised near the melting point at this time and slight temperature changes can melt glacier ice and provide liquid runoff to surrounding soil, stream, and lake ecosystems. The discharge from principal streams in the dry valleys decreased nonlinearly over this time period causing lake levels to recede and the permanent lake ice to thicken.
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Patricia Yager discussed productivity, food web dynamics, and benthic-pelagic coupling. The shallow northern Bering and southern Chukchi Sea shelf ecosystem is characterized by high, diatom-based primary production in the water column and efficient export from the surface layer to the shallow sediments, feeding a large and diverse benthic community that is critical for benthic-feeding marine mammals and seabirds.
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. The ecosystem structure changes are influencing food web dynamics as well as affecting traditional native subsistence hunting communities that must now travel longer distances in open water to hunt.
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Sharon Stammerjohn addressed many of the seasonal sensitivities and changes in regions of rapid sea ice decline, including changes occurring in the Western Antarctic Peninsula, during a plenary session at the workshop. The Western Antarctic Peninsula region has warmed in winter by +6°C since 1950 (Vaughan et al., 2003)
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The case of Adélie penguins is valuable because these ocean-foraging, land-breeding birds appear to be responding to both marine and terrestrial forcings. Their decline has roughly paralleled the regional decline in sea ice extent and duration, and also declines in favored prey species including the Antarctic krill (Euphausia superba)
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, further complicating the effects of warming and ice loss on marine ecosystem structure.
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